Peroxide-based bleaching agents (e.g., hydrogen peroxide, sodium percarbonate, sodium persulfate, sodium perphosphate, urea peroxide, and sodium perborate) act as effective oxidizers for whitening substrates, removing stains, and disinfecting surfaces. Peroxide-based bleaching agents promote a bleaching effect on organic materials and thus are used with detergents in cleaning compositions, and are also used for bleaching textiles and paper, among other applications. The bleaching effect is particularly strong in washing and cleaning processes.
Generally, to clean a soiled substrate such as clothing, the substrate is treated with hydrogen peroxide or a substance capable of generating perhydroxyl ions (HOO—), such as inorganic or organic peroxides as exemplified above. Upon contact with the surface of the soiled substrate, the peroxide effectively removes common stains such as coffee or wine, while disinfecting the surface. Compared to more volatile hypochlorite-based bleaches, peroxide-based bleaching agents exhibit environmental benefits including enhanced safety and reduced pollution. However, peroxide-based bleaching agents do not perform at the same level of cleaning efficacy as hypochlorite-based bleaches.
Peroxide bleach activating agents, or bleach activators, such as, for example, acyl compounds (e.g., tetraacetylethylenediamene (TAED)) and ester compounds (e.g., isononanoyloxybenzenesulfonate (ISONOBS) and nonanoyloxybenzene-sulfonate (NOBS)), and the like, can be added to boost activity of peroxide-based bleaching agents. It has been found that the level of peroxide bleaching activity typically generated at 95° C. by peroxide alone can be achieved at 60° C. with the addition of bleach activators. The bleach activator reacts in the presence of the peroxide-based bleaching agent to generate peracetic acid, which is a more potent oxidizer than hydrogen peroxide.
Liquid formulations containing such bleach activators have met limited consumer success due to a lack of sufficient stability. When the liquid compositions are formulated with dissolved peroxide compounds, the resulting composition is especially unstable, and thus, prone to rapid loss of bleaching efficacy. To prolong stability, the cleaning composition containing peroxide and bleach activator is typically packaged with the actives physically segregated or in an anhydrous environment. This can be achieved by dispersing the actives either in a suspension segregating the peroxide and bleach activator in different liquid phases or blending them in a dry powder form.
Powder and dual-phase liquid formulations are generally less desirable especially for consumer use as compared to other forms of cleaning compositions. Even when maintained in an anhydrous environment (i.e., powder and dual-phase liquid), the bleach activator can still react with the peroxide. Over time, the bleach activator and peroxide degrade leading to reduced efficacy.
Accordingly, there is a need for a unit dose cleaning product for delivering a peroxide-containing bleaching agent that is formulated to alleviate the limitations described above and which prevents premature degradation of the peroxide-containing bleaching agent. There is a further need for a unit dose cleaning product for delivering a peroxide-containing bleaching agent comprising a cleaning composition of the peroxide-based bleaching agent and a peroxide bleach activating agent, having improved stability over time, while enhancing convenience and ease of use for the consumer. There is also a need for a unit dose cleaning product for delivering a peroxide-containing bleaching agent that promotes cleaning of substrates in a more environmentally-friendly manner.